Conventionally, a vehicle seat adjustment apparatus may be provided in a seat of a vehicle to adjust the height of the seat cushion. For example, as described in Patent Document 1, a seat adjustment apparatus of a vehicle includes two pairs of lifter links that support a seat cushion. The lifter links of each of the pairs are arranged below the seat cushion and spaced from each other along the direction of the width of the seat cushion. The pair of the lifter links that are located at front positions are connected together through a cylindrical torque rod. The torque rod is passed through a through hole extending through an upper rail, which is arranged below the seat cushion. The lifter links that are located at the front positions are thus pivoted with the torque rod rotating with respect to the upper rail. This selectively raises and lowers the seat cushion.
A torsion bar is received in the torque rod. Elastic force produced by the torsion bar applies torque to the torque rod. The torque acts on the lifter links as assistance force that acts to raise the seat cushion. In other words, the assistance force applied from the torque rod to the lifter links facilitates raising of the seat cushion.
Patent Document 1: Japanese Laid-Open Patent
Publication No. 10-095255.